Pressure equalizing means for compressors and the like



24, 1967 B. w. ROMERHAUS 3,348,764

PRESSURE EQUALIZING MEANS FOR COMPRESSORS AND THE LIKE 2 SheetsSheet Filed Oct. 21, 1965 Ill IIiLll INVEN T0)? ATTORNEYS United States Patent 3,348,764 PRESSURE EQUALIZDIG MEANS FOR COM- PRESSORS AND THE LIKE Bert W. Romerhaus, Haubstadt, Ind., assignor to Whirlpool Corporation, a corporation of Delaware Filed Oct. 21, 1965, Ser. No. 499,246 7 Claims. (Cl. 230-22) ABSTRACT OF THE DISCLOSURE A pressure equalizing device for a compressor wherein a gravity biased valve member is normally in a position permitting communication between the compressor inlet and outlet to equalize pressure across the compressor and wherein the valve member is responsive to a pressure differential across two points in the compressor discharge passages to terminate communication between the compressor inlet and outlet. A restriction on the high pressure side of the valve member causes a delayed reaction of the valve member to the pressure differential.

This invention relates to compressors, pumps, and the like, and in particular to means for providing facilitated start-up of a compressor.

In compressors of the type conventionally in use for refrigeration apparatus, the repeated cycling of the system places a severe strain on the electric motor normally provided for driving the compressor. More specifically at start-up the substantial pressure normally occurring between the suction and discharge side of the compressor requires that the electric motor develop a high starting torque. Thus, motors, such as split phase motors, having a relatively low starting torque cannot be satisfactorily employed without incorporating some means to unload, i.e. effectively eliminate this high pressure differential in the compressor during the start-up periods. While a number of different devices have heretofore been developed for this purpose, none have proven completely satisfactory. The present invention is directed to an improved means for unloading the compressor during the start-up period to permit the start-up with effectively minimized torque requirement, and automatically subsequently restoring the compressor to the normal operating arrangement wherein the desired pressure differential is obtained between the suction and discharge sides of the compressor.

Thus, a principal feature of the present invention is the provision of new .and improved start-up, pressure unloading means for use in a compressor or the like.

A further feature of the invention is the provision of such start-up means having extremely simple and economical construction.

Another feature of the invention is the provision of such a start-up means for use in a compressor having means responsive to gravity for controlling the unloading operation.

Still another feature of the invention is the provision of such an unloading means having new and improved means for effecting a desired time delay to provide a preselected duration of the unloaded start-up operation.

A yet further feature of the invention is the provision of a compressor having means defining a pressure chamber, means defining a suction chamber, and means for pumping fluid from the suction chamber to the pressure chamber, means for causing the pressure in the pressure chamber and suction chamber to be substantially equal during initiation of operation of the pumping means and permitting the chambers to have a pressure differential therebetween during subsequent operation of the pumping means, comprising means defining an equalization passage between the pressure chamber and suction cham- 3,348,764 Patented Oct. 24, 1967 ber, means for closing the equalization passage as a result of initiation of operation of the pumping means including valve means having a movable valve member for selectively closing the equalization passage, and means biasing the valve member to open the equalization passage when the pumping means is inoperative, and means for applying pressure developed by operation of the pumping means to the valve means for delayedly moving the valve member in opposition to the biasing means to close the equalization passage after a preselected period of time.

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a fragmentary diametric vertical section of a compressor having unloading means embodying the invention;

FIGURE 2 is a fragmentary diametric vertical section taken substantially at right angles to the section of FIG- URE 1;

FIGURE 3 is a fragmentary diametric section generally similar to that of FIGURE 1, but illustrating a compressor having a modified form of unloading means embodying the invention; and

FIGURE 4 is a fragmentary vertical diametric section of still another compressor having another modified form of unloading means embodying the invention.

In the exemplary embodiment of the invention as disclosed in FIGURES 1 and 2 of the drawing, a compressor generally designated 10 is shown to comprise a housing, or dome, 11 defining a pressure chamber 12. Fluid such as refrigerant gas is compressed in compressor 10 by means of a rotor 13 provided in a cylinder 14 and driven by a motor shaft 15 rotatably carried in a front head, or hub, 16. As seen in FIGURE 1, the low pressure refrigerant gas is delivered to the rotor chamber 17 through a suction line 18 provided with a check valve 19 for preventing reverse flow of the refrigerant gas therein. As shown, the refrigerant gas flows through a suction chamber 20 in front head 16 in passing from the suction line 18 into the rotor chamber 17.

The high pressure refrigerant gas is delivered from the rotor chamber 17 into a pump outlet chamber 40 and thence through a transfer passage 21 into a series of muffler chambers 22 disposed in the rear head 23 of the compressor. From the last muffler chamber 22a, the high pressure gas is delivered through an outlet conduit 24 to external apparatus such as precooler 25, and then back into the dome chamber 12 through an inlet conduit 26. As some pressure drop occurs in passing through the external apparatus 25, the high pressure gas in dome chamber 12 is at a pressure slightly lower than the pressure of the gas in mufller chamber 22a, illustratively 2 or 3 p.s.i. less.

As best seen in FIGURE 2, the front head 16 is provided with a bore defining a valve chamber 27 in which is movably mounted a valve member 28. Valve member 28 herein comprises a cylindrical slug biased by gravity to rest in the bottom of the chamber 27 on the upper surface 29 of the rotor cylinder 14. Front head 16 is provided with a corner portion 16a which is engaged by the valve member 28 to limit the upward movement thereof. Although not shown, the valve member 28 could be biased to rest at the bottom of chamber 27 by a spring located between corner portion 16a and the top of valve member 28. An equalizing passage 30 is provided in the front head 16, having a first portion 30a communicating between the dome chamber 12 and the valve chamber 27,-

the valve member is resting on the upper surface 29 of cylinder 14. As further shown in FIGURE 2,, a restrictive passage 31 provides communication between the valve chamber 27 and the muffler chamber 22a, the passage 31 including a first portion 310 in the cylinder 14 and a second, continuing lower portion 31b in the rear head 23. The valve member 28 herein comprises a relatively heavy slug of material such as a metal. The transverse area of the valve chamber 27 is preferably substantially larger than the transverse area of the restrictive passage 31. In the preferred embodiment, passage 31 has a diameter of 0.025 inch.

When not operating, the compressor will be arranged as shown in FIGURE 2 of the drawing with the valve member 28 in the lowermost position permitting communication through passage between the domechamber 12 and the suction chamber 20, thereby equalizing the pressure on the opposite sides of the rotor and, thus, unloading thecompressor. When operation of the rotor 13 is commenced by rotation of motor shaft 15, the unloaded condition of the compressor permits the motor to readily start the operation of the compressor with minimum torquerequirements. As the pressure of the gas delivered into the pump outlet chamber builds up, the pressure correspondingly builds up in the muffler chambers 22. The increased pressure in mufiler chamber 22a is delivered through restrictive passage 31 against the bottom of valve member28 tending to raise the valve member from its seated position on the upper surface 29 of the cylinder 14. Because of the restrictive nature of passage 31 and the pressure drop through it, the valve member 28 will not immediately be thrown upwardly to block off passage 30. After several revolutions of the rotor 13, the pressure behind the valve member slug 28 will be the same as that within the muffler chamber 22a since there will no longer be flow of gas through passage 31 and, hence, it will become ineffective as a restrictor. At this time, the pressure within the dome acting. on the upper end of slug 28 will be slightly lower than the pressure on the underside of the slug 28 as explained above. This small pressure differential will cause the slug 28 to remain in its raised position to thereby block off passage 30. The specific length of time to effect this blockage of the passage 30 is obviously a function of the transverse area of the restrictive passage 31, the transverse area of the chamber 27, the weight of the valve member 28, and the pressure differential existing between the dome chamber pressure 12 and the pressure in muffler chamber 22. Suitable selection of these parameters may be made, as will be obvious to those skilled in the art, to obtain a desired duration of the unloaded start-up condition. Thus, the drive of rotor 13 may be by means of a relatively inexpensive, low-starting torque motor such as a split phase motor while yet the compressor operation is efiiciently and quickly started.

The raised position of the valve member slug 28 is maintained during the operation of the compressor, thereby assuring efiicient conventional operation of the compressor for providing compressed fluid to external apparatus as desired. As shown in FIGURE Z, the high pressure gas may be delivered from the dome chamber 12 through an outlet conduit 32 to conventional refrigeration apparatus, such as a condenser 33, capillary tube 34 and evaporator 35. The low pressure refrigerant gas is returned from the external apparatus through the suction line 18 for recompression with the rotor chamber 17 as discussed above.

Turning now to the embodiment of the invention disclosed in FIGURE 3, a modified compressor generally designated 110 is shown to comprise a compressor generally similar to compressor 10, but having a modified means for unloading the compressor during the start-up operation wherein a passage 131 is provided in the front head 116 to provide communication between the bore 127 and the pump outlet chamber 140. The passage 131 is provided with a restricted portion 131a for controlled, restricted flow of the high pressure refrigerant gas from the pump outlet chamber 140 to the enlarged cavity portion 13112 and thence to the valve chamber 127. The valve member 128 is generally similar to valve member 28, except that it is provided with a lower portion 128a, and an upper portion 128b which is smaller in transverse section than the lower portion 128a. As shown in FIG- URE 3, the reduced portion 128]: is aligned with the portions 130a and 13% of the passage 130 when the valve member is in the lowermost position resting on the surface 129 defining the bottom of the bore 127. Thus, fluid may flow freely around the reduced portion 128]) and through passage portion 130b into the suction chamber at this time. When, however, the valve member 128 is raised by the differential between the dome chamber 112 pressure and the pressure acting on the underside of the valve member as delivered through the passage 131 from the pump outlet chamber 140, the large lower portion 128a of the valve member becomes aligned with the equalization passage portions a and 13011, thereby blocking the passage and preventing further communication between the dome chamber 112 and the suction chamber 120. Thus, for any given diameter of bore 127, the valve member 128 of FIGURE 3 is heavier than that of valve member 28 embodied in FIGURE 2 because of the additional mass added in the upper reduced portion 12812. Depending upon the valves of the other various design parameters, this additional weight of the valve member may be necessary in order to achieve the desired time delay in lifting the valve member to its raised position during compressor start-up.

' As shown in FIGURE 3, the front head 116 includes a corner portion 116a which is engaged by valve portion 128b at the uppermost extreme of its movement, thereby limiting the movement of the valve member and maintaining the lower portion 12811 in passage blocking position during the operation of the compressor 110.

As discussed above relative to compressor 10, the spe-:

cific parameters of the area of the passage 131, the area of thebore 127, the weight of the valve member 128 and the pressure differential between pump outlet chamher and dome chamber 112 may be selected by one skilled in the art to obtain a desired time delay for providing the desired unloaded start-up operation. As in the case of the embodiment shown in FIGURE 2, the restricted portion 131a may comprise an opening of approximately 0.025 inch in diameter. In addition to the variables mentioned above, the embodiment shown in FIGURE 3 introduces a further parameter in obtaining a time delay operation of valve member 128. Thus, the provision of the enlarged cavity portion 131b of passage 131 upstream of the restricted portion 131a results in increased time delay and, hence, the volume of this enlarged portion 131i; along with the other parameters mentioned can be chosen to give the valve member the desired amount of time delay during start-up of the compressor.

Thus, compressor 110 functions generally similar to compressor 10 except that in compressor 10 the restricted passage 31 is connected to the last mufiier chamber, whereas in compressor 110, the passage 131, .with its restricted portion 131a, is connected directly to the pump. outlet chamber. Connecting the passage 31 to the last muffler cavity, as done in compressor 10, has the advantage of making valve member 28 less sensitive to pressure pulses occurring in the pump outlet chamber 40. On the other hand, connecting the passage 131 to pump outlet chamber 140, as done in compressor 110,results in a greater pressure differential between the dome chamber 112 and the underside of the valve member 128 which, depending upon the valves of the other design parameters, may be a necessary requirement. As is obvious to those skilled in the art, the slightly different structures of the valve members 28 and 128 may be used interchangeably. The other portions of the compressor 110 which are similar to those of compressor require no further description here, it being understood that similar parts are identified by similar reference numerals except one hundred higher in compressor 110.

Referring now to FIGURE 4, a further modified form of compressor generally designated 210 is shown to comprise a compressor generally similar to compressor 10, but reversely arranged in that the uppermost head of the compressor comprises the rear head 223 with the suction line 218 being connected to the front head 216 for delivering the low pressure gas to the suction chamber 220 under the control of the check valve 219. The suction chamber 220 is placed in communication with the dome chamber 212 by means of an equalizing passage 230 having a first portion 230a communicating between the dome chamber 212 and a valve chamber 227 in the rear head 223, and a second portion 23% communicating between the valve chamber 227 and the suction chamber 220. A slug type valve member 228 is provided in the valve chamber and is arranged to rest under the influence of gravity on a surface 229 defining the lower end of a recess 229a in the cylinder 214 and comprising a downward extension of the valve chamber 227. The recess 229a is in communication with the muifier cavity 222a through a passage 23 1 in the cylinder 214.

Compressor 210 functions generally similar to compressor 10 in that the rotor is unloaded in the de-energized condition of the compressor by the downward movement of the valve member slug 228 to unblock the passage 230 between the suction chamber 220 and the dome chamber 212. However, as the pressure builds up in the mufller chamber 222a upon initiation of operation of the compressor, the valve member slug 228 is delayedly moved upwardly against stop 241 to close the passage 230 after a pre-selected time whereby unloaded start-up of the compressor is obtained.

In all other respects, compressor 210 is similar to and functions similar to compressor 10. Elements. of compressor 210 which are identical to elements of compressor 10 are identified by similar reference numerals but two hundred higher.

Thus, in each of compressors 10, 110 and 210', new and improved means are provided for equalizing the pressure at the suction and discharge sides of the compressor rotor at the time of start-up of the compressor. After a preselected time interval, the equalization of the two pressures is automatically discontinued and the high dome pressure is segregated from the suction pressure for normal continued operation of the compressor in the conventional manner. The pressure equalizing means of the present invention, is extremely simple and economical of construction utilizing a simple gravity biased valve member providing long trouble-free life. The invention comprehends that movement of the valve member to the equalizing-passage closing position be controlledly delayed so as to provide the unloaded start-up duration. This desired time delay is illustratively obtained by suitable restrictive means which limit the flow of fluid to or from the valve chamber. The compressor may be of the generally conventional hermetically sealed type as disclosed in the illustrated embodiments, including the inverted type as illustrated in the FIGURE 4 embodiment, or as will be obvious to those skilled in the art may be of any suitable construction permitting the provision of the desired equalizing passage and valve control means to provide the novel time delay control of the equalized start-up as disclosed.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claims.

The embodiments of the invention in which an ex- 6 elusive property or privilege is claimed are defined as follows:

1. In a compressor having means defining a pressure chamber, means defining a suction chamber, means defining a dome chamber, and means for pumping fluid from said suction chamber to said pressure chamber, means for causing the pressure in said pressure chamber and suction chamber to be substantially equal during initiation of operation of said pumping means and means causing the pressure and dome chambers to have a pressure differential therebetween during subsequent operation of the pumping means, comprising:

means defining an equalization passage between said dome chamber and suction chamber;

means for closing said equalization passage as a result of initiation of operation of said pumping means including valve means having a movable valve member for selectively closing said equalization passage, and means biasing said valve member to open said equalization passage when the pumping means is inoperative; and

means for applying said pressure differential developed by operation of said pumping means to said valve member for delayedly moving said valve member in opposition to the biasing thereof to close said equalization passage after a preselected period of time.

2. The compressor means of claim 1 wherein said pressure differential applying means comprises a delivery passage for conducting fluid from said pressure chamber to said valve means and having means therein for throttling fluid flow therethrough.

3. The compressor means of claim 2 wherein said throttling means comprises a fixed restriction means.

4. The compressor means of claim 1 further including means for maintaining the pressure differential across the valve member and thereby maintain said valve member in the equalization passage-closing position during subsequent operation of the pumping means.

5. The compressor means of claim 1 wherein said valve means comprises means defining a bore intersecting said equalizationpassage and having an inlet opening to said pressure chamber and said valve member comprises a slug movable in said bore by said pressure differential against the Weight thereof for selectively blocking said equalization passage.

6. In a compressor having means defining a pressure chamber, means defining a suction chamber, and means for pumping fluid from said suction chamber to said pressure chamber, means for causing the pressure in said pressure chamber and suction chamber to be substantially equal during initiation of operation of said pumping means and permitting the chambers to have a pressure differential therebetween during subsequent operation of the pumping means, comprising:

means defining an equalization passage between said pressure chamber and suction chamber;

means for closing said equalization passage as a result of initiation of operation of said pumping means including valve means having a movable valve member for selectively closing said equalization passage, and means biasing said valve member to open said equalization passage when the pumping means'is inoperative; and

means for applying pressure developed by operation of said pumping means to said valve means for delayedly moving said valve member in opposition to said biasing means to close said equalization passage after a preselected period of time, said pressure applying means comprising a delivery passage for conducting fluid from said pumping means to said valve means, said delivery passage having a first restricted portion and a second enlarged cavity portion upstream from said first restricted portion.

7. In a compressor having means defining a pressure chamber, means defining a suction chamber, and means for pumping fluid from said suction chamber to said pressure chamber, means for causing the pressure in said pressure chamber and suction chamber to be substantially equal during initiation of operation of said pumping means and permitting the chambers to have a pressure diiferential therebetween during subsequent operation of the pumping means, comprising:

means defining an equalization passage between said pressure chamber and suction chamber;

means for closing said equalization passage as a result of initiation of operation of said pumping means inand spaced from alignment with said inlet and outlet with said lower portion disposed to block said fluid flow.

eluding valve means having a movable valve member for selectively closing said equalization passage, and means biasing said valve member to open said equalization passage when the pumping means is inoperative; and

means for applying pressure developed by operation of said pumping means to said valve means for delayedly moving said valve member in opposition to said biasing means to close said equalization passage after a preselected period of time, said valve means comprising means defining a bore, said equalization passage having an inlet opening into said bore and an outlet opening outwardly from said bore, said 10 References Cited UNITED STATES PATENTS 711,689 10/ 1902 Wittenmeier 230--22 831,522 9/1906 Reardon 23o 22 876,359 1/1908 Karger 230-22 1,128,077 2/1915 Taylor 103-42 1,911,105 5/1933 Buchler 230-22 1,934,758 11/1933 Temple 103- 42 1,965,420 7/1934 Lipman 230-22 2,373,909 4/1945 Penn 230-24 2,470,565 5/1949 Loss 230-22 DONLEY J. STOCKING, Primal Examiner.

25 W. J. KRAUSS, Assistant Examiner. 

7. IN A COMPRESSOR HAVING MEANS DEFINING A PRESSURE CHAMBER, MEANS DEFINING A SUCTION CHAMBER, AND MEANS FOR PUMPING FLUID FROM SAID SUCTION CHAMBER TO SAID PRESSURE CHAMBER, MEANS FOR CAUSING THE PRESSURE IN SAID PRESSURE CHAMBER AND SUCTION CHAMBER TO BE SUBSTANTIALLY EAUAL DURING INITIATION OF OPERATION OF SAID PUMPING MEANS AND PERMITTING THE CHAMBERS TO HAVE A PRESSURE DIFFERENTIAL THEREBETWEEN DURING SUBSEQUENT OPERATION OF THE PUMPING MEANS, COMPRISING: MEANS DEFINING AN EQUALIZATION PASSAGE BETWEEN SAID PRESSURE CHAMBER AND SUCTION CHAMBER; MEANS FOR CLOSING SAID EQUALIZATION PASSAGE AS A RESULT OF INITIATION OF OPERATION OF SAID PUMPING MEANS INCLUDING VALVE MEANS HAVING A MOVABLE VALVE MEMBER FOR SELECTIVELY CLOSING SAID EQUALIZATION PASSAGE, AND MEANS BIASING SAID VALVE MEMBER TO OPEN SAID EQUALIZATION PASSAGE WHEN THE PUMPING MEANS IS INOPERATIVE; AND MEANS FOR APPLYING PRESSURE DEVELOPED BY OPERATION OF SAID PUMPING MEANS TO SAID VALVE MEANS FOR DELAYEDLY MOVING SAID VALVE MEMBER IN OPPOSITION TO SAID BIASING MEANS TO CLOSE SAID EQUALIZATION PASSAGE AFTER A PRESELECTED PERIOD OF TIME, SAID VALUE MEANS COMPRISING MEANS DEFINING A BORE, SAID EQUALIZATION PASSAGE HAVING AN INLET OPENING INTO SAID BORE, SAID AN OUTLET OPENING OUTWARDLY FROM SAID BORE, SAID VALVE MEMBER COMPRISING A SLUG MOVABLE IN SAID BORE FOR SELECTIVELY BLOCKING FLOW FLUID BETWEEN SAID INLET AND OUTLET, AND SAID SLUG INCLUDING A LOWER PORTION AND A TRANSVERSELY REDUCED UPPER PORTION, SELECTIVELY ALIGNED WITH SAID INLET AND OUTLET AND PERMITTING FLUID FLOW THEREAROUND THROUGH SAID BORE, AND SPACED FROM ALIGNMENT WITH SAID INLET AND OUTLET WITH SAID LOWER PORTION DISPOSED TO BLOCK SAID FLUID FLOW. 